On Tue, Nov 23, 2021 at 11:11 PM Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:
>
> One word about the pm_ptr() macro. Right now it's defined as:
> #ifdef CONFIG_PM
> #define pm_ptr(_ptr) (_ptr)
> #else
> #define pm_ptr(_ptr) NULL
> #endif
>
> It could be possible to define it like this instead:
> #define pm_ptr(_ptr) PTR_IF(IS_ENABLED(CONFIG_PM), (_ptr))
>
> The difference is that if !CONFIG_PM, in the first case the (_ptr) is
> not visible by the compiler and the __maybe_unused is required, while
> in the second case the (_ptr) is always visible by the compiler, but
> discarded as dead code. The reason we'd want that is the same reason we
> use IS_ENABLED() instead of macro guards; and you wouldn't need the
> __maybe_unused attribute anywhere.
That sounds like a great idea. I see there are only 12 users of pm_ptr at
the moment, so auditing all of these should not be a problem.
I gave it a brief look and found that we probably only need to fix
drivers/net/ethernet/realtek/r8169_main.c if we change the definition.
> The problem then is that the SET_*_PM_OPS macros are defined
> differently according to CONFIG_PM, so their definition would need to
> be changed to use the (redefined) pm_ptr() macro and a corresponding
> pm_sleep_ptr() macro. Unfortunately since the SET_*_PM_OPS macros are
> used everywhere with code wrapped around #ifdef CONFIG_PM guards, it
> wouldn't be easy to change them, and it would just be easier to
> introduce new macros.
Right, this is what we've discussed multiple times, and I think everyone
agreed we should do this, but so far we could not come up with a name
for the new macro, and changing the macro in place is not practical unless
we change hundreds of drivers in the same way as the iio series first.
Arnd
